Protector for electrical submersible pumps

ABSTRACT

A system and method is used to protect a motor of a submersible pumping system. A variety of motor protector features are provided to facilitate operation of the motor protector and submersible pumping system in multiple wellbore environments and applications.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. Ser. No. 10/907,976, filed Apr. 22, 2005,which is a continuation of U.S. Ser. No. 10/727,922, now U.S. Pat. No.6,981,853 filed Dec. 4, 2003, which is a divisional of U.S. Ser. No.10/059,795, now U.S. Pat. No. 6,688,860, filed Jan. 29, 2002, whichclaims the benefit under 35 C.S.C. 119(e) to U.S. ProvisionalApplication No. 60/303,860 filed Jul. 9, 2001 and prior ProvisionalApplication No. 60/299,013 filed Jun. 18, 2001.

FIELD OF THE INVENTION

The present invention relates generally to motor protectors forprotecting submersible motors, such as those used in raising fluids frompetroleum wells. More particularly, the present invention relates to amotor protection system and method comprising one or both of a protectedbellows assembly and a three-dimensional labyrinth assembly.

BACKGROUND OF THE INVENTION

A variety of production fluids are pumped from subterraneanenvironments. Different types of submersible pumping systems may bedisposed in production fluid deposits at subterranean locations to pumpthe desired fluids to the surface of the earth.

For example, in producing petroleum and other useful fluids fromproduction wells, it is generally known to provide a submersible pumpingsystem for raising the fluids collected in a well. Production fluids,e.g. petroleum, enter a wellbore drilled adjacent a productionformation. Fluids contained in the formation collect in the wellbore andare raised by the submersible pumping system to a collection point at orabove the surface of the earth.

A typical submersible pumping system comprises several components, suchas a submersible electric motor that supplies energy to a submersiblepump. The system further may comprise a variety of additionalcomponents, such as a connector used to connect the submersible pumpingsystem to a deployment system. Conventional deployment systems includeproduction tubing, cable and coiled tubing. Additionally, power issupplied to the submersible electric motor via a power cable that runsthrough or along the deployment system.

Often, the subterranean environment (specifically the well fluid) andfluids that are injected from the surface into the wellbore (such asacid treatments) contain corrosive compounds that may include CO₂, H₂Sand brine water. These corrosive agents can be detrimental to componentsof the submersible pumping system, particularly to internal electricmotor components, such as copper windings and bronze bearings. Moreover,irrespective of whether or not the fluid is corrosive, if the fluidenters the motor and mixes with the motor oil, the fluid can degrade thedielectric properties of the motor oil and the insulating materials ofthe motor components. Accordingly, it is highly desirable to keep theseexternal fluids out of the internal motor fluid and components of themotor.

Submersible electric motors are difficult to protect from corrosiveagents and external fluids because of their design requirements thatallow use in the subterranean environment. A typical submersible motoris internally filled with a fluid, such as a dielectric oil, thatfacilitates cooling and lubrication of the motor during operation. Asthe motor operates, however, heat is generated, which, in turn, heatsthe internal motor fluid causing expansion of the oil. Conversely, themotor cools and the motor fluid contracts when the submersible pumpingsystem is not being used.

In many applications, submersible electric motors are subject toconsiderable temperature variations due to the subterranean environment,injected fluids, and other internal and external factors. Thesetemperature variations may cause undesirable fluid expansion andcontraction and damage to the motor components. For example, the hightemperatures common to subterranean environments may cause the motorfluid to expand excessively and cause leakage and other mechanicaldamage to the motor components. These high temperatures also may destroyor weaken the seals, insulating materials, and other components of thesubmersible pumping system. Similarly, undesirable fluid expansion andmotor damage can also result from the injection of high-temperaturefluids, such as steam, into the submersible pumping system.

Accordingly, this type of submersible motor benefits from a motor fluidexpansion system able to accommodate the expanding and contracting motorfluid. The internal pressure of the motor must be allowed to equalize orat least substantially equalize with the surrounding pressure foundwithin the wellbore. As a result, it becomes difficult to prevent theingress of external fluids into the motor fluid and internal motorcomponents.

Numerous types of motor protectors have been designed and used inisolating submersible motors while permitting expansion and contractionof the internal motor fluid. A variety of elastomeric bladders alone orin combination with labyrinth sections have been used as a barrierbetween the well fluid and the motor fluid. For example, expandableelastomeric bags or bladders have been used in series to prevent mixingof wellbore fluid with motor fluid while permitting expansion andcontraction of the motor fluid.

In this latter design, the motor protector includes a pair of chamberseach of which have an elastomeric bladder. The first bladder is disposedin a first chamber of the pair of chambers and includes an interior influid communication with the motor. This fluid communication permitsmotor oil to flow from the motor into the elastomeric bladder duringexpansion and to flow from the elastomeric bladder back to the motorduring contraction.

The second chamber also has an expandable bladder, filled with motoroil, which is in fluid communication with the first chamber but externalto the first elastomeric bladder. The second chamber is vented or opento the wellbore environment. This assembly permits fluid to flow betweenthe second elastomeric bladder and the adjacent chamber as the firstelastomeric bladder expands or contracts. Simultaneously, wellbore fluidis allowed to flow in and out of the second chamber, external to thesecond elastomeric bladder, to permit equalization of pressure as thesecond bladder expands and contracts.

This type of expansion chamber works well in many environments, butcertain of the corrosive agents found in at least some wellboreenvironments comprise corrosive gases that permeate the elastomeric bagsor bladders. These corrosive agents eventually can work their way intothe motor oil within the first elastomeric bladder and ultimatelycorrode and damage internal components of the electric motor. Thewellbore environment also may have an undesirable temperature (e.g.,hot), which may destroy the elastomeric bag or bladder and the shaftseal materials throughout the submersible pumping system.

The conventional labyrinth type protector uses the difference inspecific gravity of the well fluid and the motor fluid to separate thefluids. For example, a typical labyrinth may embody a chamber having afirst passageway to the motor fluid and a second passageway to anundesirable fluid, such as fluids in the wellbore. The first and secondpassageways are generally oriented on opposite sides of the chamber tomaintain fluid separation in a vertical orientation. Accordingly,conventional labyrinth type protectors are generally less effective, ortotally useless, in orientations deviated from the vertical orientation.

Accordingly, the need exists for improved motor protectors, which areoperable in variable temperature applications and multiple orientations.For example, it would be advantageous to position a bellows assemblybetween a motor fluid and an external fluid and positively pressurizethe motor fluid relative to the external fluid to prevent inward leakageof the external fluid into the motor. It also would be advantageous toprovide a relatively balanced bellows assembly having one or both endsfixed, rather than using sliding seals. Moreover, it would beadvantageous to provide a multi-orientable labyrinth having conduitsextending in multiple orientations to maintain fluid paths having peaksand valleys in all potential orientations.

SUMMARY OF THE INVENTION

The present invention features a system and method for protecting amotor of a submersible pumping system. A variety of motor protectorfeatures are provided to facilitate operation of the motor protector andsubmersible pumping system in multiple wellbore environments andapplications.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereafter be described with reference to theaccompanying drawings, wherein like reference numerals denote likeelements, and:

FIG. 1 is a front elevational view of an exemplary pumping systemdisposed within a wellbore;

FIG. 2 is a diagrammatical cross-section of the pumping system having abellows assembly to separate well fluid from motor fluid, which ispositively pressurized within the motor housing;

FIG. 3 is a front elevational view of an exemplary configuration of thepumping system having a seal section and bellows section disposed aboutthe submersible motor;

FIG. 4 is a cross-sectional view of the seal section;

FIGS. 5A and 5B are cross-sectional views of the bellows section;

FIG. 6 is a diagrammatical cross-section of an alternate embodiment ofthe pumping system having multiple motor protection assemblies disposedabout the submersible motor;

FIGS. 7 and 8 are front elevational views of alternate configurations ofthe pumping system;

FIG. 9 is a diagrammatical cross-section of the pumping system having abellows assembly with a spring assembly;

FIG. 10 is a diagrammatical cross-section of the pumping system having abellows assembly and a hard bearing;

FIGS. 11 and 12 are cross-sectional views of alternate embodiments of abellows section;

FIG. 13 is a diagrammatical cross-section of the pumping system having amulti-orientable labyrinth assembly;

FIG. 14 is a perspective view of the multi-orientable labyrinthassembly, which is configured for disposal adjacent the bellows assemblysuch as illustrated in FIGS. 2 and 8;

FIG. 15 is a perspective view of an alternate embodiment of themulti-orientable labyrinth assembly, which has a ring-shape configuredto dispose the labyrinth assembly about the shaft as illustrated in FIG.13;

FIGS. 16A and 16B are cross-sectional views of the pumping systemillustrating an alternate embodiment having both the bellows assemblyand the multi-orientable labyrinth assembly; and

FIG. 17 is a cross-sectional view of an alternate bellows section havingmultiple bellows assemblies.

DETAILED DESCRIPTION

Referring generally to FIG. 1, an exemplary pumping system 10, such as asubmersible pumping system, is illustrated. Pumping system 10 maycomprise a variety of components depending on the particular applicationor environment in which it is used. Typically, system 10 has at least asubmersible pump 12, a motor 14 and a motor protector 16. Motor 14 maycomprise any electric motor or other motor that requires volumecompensation based on, for instance, the thermal expansion and/orcontraction of internal fluid. The submersible pump 12 may be of avariety of types, e.g. a centrifugal pump, an axial flow pump, or amixture thereof. The system 10 may also comprise a gearbox, as is knownin the art.

In the illustrated example, pumping system 10 is designed for deploymentin a well 18 within a geological formation 20 containing desirableproduction fluids, such as petroleum. In a typical application, awellbore 22 is drilled and lined with a wellbore casing 24. Wellborecasing 24 typically has a plurality of openings 26, e.g. perforations,through which production fluids may flow into wellbore 22.

Pumping system 10 is deployed in wellbore 22 by a deployment system 28that may have a variety of forms and configurations. For example,deployment system may comprise tubing 30 connected to pump 12 by aconnector 32. Power is provided to submersible motor 14 via a powercable 34. Motor 14, in turn, powers centrifugal pump 12, which drawsproduction fluid in through a pump intake 36 and pumps the productionfluid to the surface via tubing 30.

It should be noted that the illustrated submersible pumping system 10 ismerely an exemplary embodiment. Other components can be added to thesystem, and other deployment systems may be implemented. Additionally,the production fluids may be pumped to the surface through tubing 30 orthrough the annulus formed between deployment system 28 and wellborecasing 24. In any of these configurations of submersible pumping system10, it is desirable to attain maximum protection and life of the motorfluid, the motor 14 and the motor protector 16 in accordance with thepresent invention.

In the present invention, the system 10 may have multiple sections ofthe motor protector 16 disposed about the motor 14. A diagrammaticalcross-sectional view of an exemplary embodiment of the system 10 isprovided in FIG. 2. As illustrated, the system 10 comprises the pump 12,motor 14, and various motor protection components disposed in a housing38. The pump 12 is rotatably coupled to the motor 14 via a shaft 40,which extends lengthwise through the housing 38 (e.g., one or morehousing sections coupled together). The system 10 and the shaft 40 mayhave multiple sections, which can be intercoupled via couplings andflanges. For example, the shaft 40 has couplings 42 and 44 and anintermediate shaft section 46 disposed between the pump 12 and the motor14. Various sections and configurations are illustrated in detail below,with reference to FIGS. 2-3, 6-13, 16 and 17.

A variety of seals, filters, absorbent assemblies and other protectionelements also may be disposed in the housing 38 to protect the motor 14.A thrust bearing 48 is disposed about the shaft 40 to accommodate andsupport the thrust load from the pump 12. A plurality of shaft seals,such as shaft seals 50 and 52, are also disposed about the shaft 40between the pump 12 and the motor 14 to isolate a motor fluid 54 in themotor 14 from external fluids, such as well fluids and particulates. Theshaft seals 50 and 52 also may include stationary and rotationalcomponents, which may be disposed about the shaft 40 in a variety ofconfigurations. The system 10 also has a plurality of moisture absorbentassemblies, such as moisture absorbent assemblies 56, 58, and 60,disposed throughout the housing 38 between the pump 12 and the motor 14.These moisture absorbent assemblies 56-60 absorb and isolate undesirablefluids (e.g., water, H2S, etc.) that have entered or may enter thehousing 38 through the shaft seals 50 and 52 or though other locations.For example, the moisture absorbent assemblies 56 and 58 are disposedabout the shaft 40 at a location between the pump 12 and the motor 14,while the moisture absorbent assembly 60 is disposed on an opposite sideof the motor 14 adjacent a bellows assembly 64. In addition, the actualprotector section above the motor may include a hard bearing head withshedder (see FIG. 10).

As illustrated in FIG. 2, the motor fluid 54 is in fluid communicationwith an interior 66 of the bellows assembly 64, while well fluid 68 isin fluid communication with an exterior 70 of the bellows assembly 64.Accordingly, the bellows assembly 64 seals the motor fluid 54 from thewell fluid 68, while positively pressurizing the motor fluid 54 relativeto the well fluid 68 (e.g., a 50 psi pressure differential). The springforce, or resistance, of the bellows assembly 64 ensures that the motorfluid 54 maintains a higher pressure than that of the well fluid 68. Aseparate spring assembly or biasing structure (e.g., as illustrated byFIG. 9 generally) also may be incorporated in bellows assembly 64 to addto the spring force, or resistance, which ensures that the motor fluid54 maintains a higher pressure than that of the well fluid 68.

The bellows assembly 64 may embody a variety of structural features,geometries and materials. For example, the bellows assembly 64 mayembody an enclosure having an annular wall formed by a plurality ofsymmetrical wall sections, such as ring-shaped wall sections, which arefoldingly collapsible and expandable with fluid pressure variations inthe system (e.g., an accordion-like enclosure). As illustrated by FIGS.2, 5A-B, 6, 10 and 17, the bellows assembly 64 provides a directseparation interface between the motor and well fluids 54 and 68 anduses the pressure of the well fluid 68 in combination with a springforce of the bellows assembly 64 to positively pressurize the motorfluid 54.

The bellows assembly 64 also may be used for pressure balancing orequalization between the motor and well fluids 54 and 68 or between themotor fluid 54 and another internal fluid of the system 10, such asillustrated in FIGS. 11, 12 and 16B. In this pressure balancingembodiment of the bellows assembly 64, the bellows assembly 64 mayembody one or more collapsible wall sections of varying cross-sections,such as annular wall sections having different diameters. As illustratedby FIGS. 11, 12 and 16B, the foregoing annular wall sections may bedisposed about a motor-to-pump shaft between the pump 12 and the motor14 for internal pressure balancing of the motor and well fluids 54 and68. However, it is understood that these bellows assemblies 64 also mayprovide some positive pressurization (e.g., 5 psi) of the motor fluid 54relative to the well fluid 68. As illustrated in FIG. 11, the bellowsassembly 64 may have concentric collapsible walls, which form a hollowring-shaped enclosure. As illustrated in FIG. 12, the foregoingcollapsible walls of the bellows assembly 64 may be disposed in astepped configuration, which has a disk-shaped wall coupling adjacentcollapsible walls. In any of the foregoing structures andconfigurations, the bellows assembly 64 may be coupled to thesubmersible pumping system at one or both ends without a sliding seat.

In any of the foregoing positive pressurization or pressure balancingconfigurations, the bellows assembly 64 may be constructed from suitablematerials that are resistant (e.g., impermeable) to the hot andcorrosive environment within the wellbore, such as Kalrez, Chemrez, orInconel 625. Accordingly, the bellows assembly 64 provides a relativelystrong fluid separation between the motor and well fluids (or otherinternal fluid of the system 10) to prevent leakage into the motor 14,to prevent undesirable contamination and corrosion of the motor 14, andto prolong life of the motor 14 and the overall system 10.

Initially, the motor fluid 54 is injected into the motor 14 and thebellows assembly 64 is pressurized until a desired positive pressure isobtained within the motor 14. For example, the system 10 may set aninitial pressure, such as 25-100 psi, prior to submerging the system 10into the well. The exterior chamber 70 adjacent the bellows assembly 64also may be filled with fluid prior to submerging the system into thewell. The well fluid 68 enters the housing 38 through ports 72 and mixeswith this fluid in exterior chamber 70 as the system 10 is submersedinto the well.

Referring now to the operation of the bellows assembly 64 illustrated byFIG. 2, the motor fluid 54 expands and contracts as the motor 14 isactivated and deactivated and as other temperature fluctuations affectthe fluid volume. If the motor fluid 54 expands, then the bellowsassembly 64 expands accordingly. If the motor fluid 54 contracts, thenthe bellows assembly 64 also contracts. The spring force of the bellowsassembly 64 ensures that the motor fluid 54 is positively pressurizedrelative to the well fluid 68, regardless of whether the motor fluid 54has expanded or contracted (e.g., 10 psi, 25 psi, 50 psi or higherpressure differential).

During or after submerging the system 10, the system 10 may release orinject oil in the motor to maintain the pressure of the motor fluid 54within a certain pressure range. Accordingly, as illustrated by thebellows configuration of FIGS. 2, 5A-B, 6, 10 and 17, the externalfluids (i.e., the well fluid 68) are continuously pressured away fromthe internal fluids (i.e., the motor fluid 54) of the motor 14 toprevent undesirable corruption of the internal fluids and components ofthe motor 14. The foregoing pressure ensures that if leakage occurs, theleakage is directed outwardly from the motor fluid 54 to the well fluid68, rather than inwardly from the well fluid 68 into the motor fluid 54(i.e., the typical undesirable leakage/corruption of the motor fluid54). The positive internal pressure generally provides a betterenvironment for the system 10. The positive pressure of the motor fluid54 provided by the bellows assembly 64 also may be used to periodicallyflush fluids through the bearings and seals to ensure that the bearingsand seals are clean and operable.

Throughout the life of the system 10, motor fluid 54 tends to leakoutwardly through the shaft seals (such as shaft seals 50 and 52) andinto the external fluids. By itself, this gradual leakage tends todecrease the pressure of the motor fluid 54. However, the bellowsassembly 64 compensates for the leakage to maintain a certain positivepressure range within motor fluid 54. In the embodiment shown in FIG. 2,the bellows assembly 64 compensates by contracting (due to the springforce). In the embodiment shown in FIGS. 5A-5B (described below), thebellows assembly 64 compensates by expanding (also due to the springforce).

The bellows assembly 64 also may have various protection elements toextend its life and to ensure continuous protection of the motor 14. Forexample, a filter 74 may be disposed between the ports 72 and theexterior 70 of the bellows assembly 64 to filter out undesirable fluidelements and particulates in the well fluid 68 prior to fluidcommunication with the exterior 70. A filter 76 also may be providedadjacent the interior 66 of the bellow assembly 64 to filter out motorshavings and particulates. As illustrated, the filter 76 is positionedadjacent the moisture absorbent assembly 60 between the motor cavity 62and the interior 66 of the bellows assembly 64. Accordingly, the filter76 prevents solids from entering or otherwise interfering with thebellows assembly 64, thereby ensuring that the bellows assembly 64 isable to expand and contract along with volume variations in the fluids.

A plurality of expansion and contraction stops also may be disposedabout the bellows assembly 64 to prevent over and under extension and toprolong the life of the bellows assembly 64. For example, a contractionstop 78 may be disposed within the interior 66 of the bellows assembly64 to contact an end section 80 and limit contraction of the bellowsassembly 64. An expansion stop 82 also may be provided at the exterior70 of the bellows assembly 64 to contact the end section 80 and limitexpansion of the bellows assembly. These contraction and expansion stops78 and 82 can have various configurations depending on the materialutilized for the bellows assembly 64 and also depending on the pressuresof the motor fluid 54 and the well fluid 68. A housing 84 also may bedisposed about the exterior 70 to guide the bellows assembly 64 duringcontraction and expansion and to provide overall protection about theexterior 70.

As discussed above, the motor fluid 54 may be pressurized significantlyprior to submersing the system 10. As the system 10 is submersed andactivated in the downhole environment, the internal pressure of themotor fluid 54 may rise and/or fall due to temperature changes, such asthose provided by the activation and deactivation of the motor 14.Accordingly, various valves may be disposed within the housing 38 tocontrol the pressurization of the motor fluid 54 and to maintain asuitable positive pressure range for the motor fluid 54. For example, avalve 86 may be provided to release motor fluid 54 when thepressurization exceeds a maximum pressure threshold. In addition,another valve may be provided to input additional motor fluid when thepressurization falls below a minimum pressure threshold. Accordingly,the valves maintain the desired pressurization and undesirable fluidelements are repelled from the motor cavity 62 at the shaft seals 50 and52.

The system 10 also may have a wiring assembly 87 extending through thehousing 38 to a component adjacent the bellows assembly 64. For example,a variety of monitoring components may be disposed below the bellowsassembly 64 to improve the overall operation of the system 10. Exemplarymonitoring components comprise temperature gauges, pressure gauges, andvarious other instruments, as should be appreciated by those skilled inthe art.

As discussed above, the system 10 may have various configurations of thebellows assembly 64 and motor protection components for the motor 14.FIG. 3 is a front elevational view of an exemplary configuration of thesystem 10, wherein the motor protector 16 comprises a seal section 88and a bellows section 90. As illustrated, the seal section 88 isdisposed between the pump 12 and the motor 14, while the bellows section90 is disposed adjacent the motor 14 on an opposite side of the sealsection 88. The system 10 also has an optional monitoring system 92disposed adjacent the bellows section 90. If additional sealing andmotor protection is desired in the system 10, then a plurality of theseal and bellows sections 88 and 90 can be disposed about the motor 14in desired locations. For example, the system 10 may have multiplebellows sections 90 disposed sequentially and/or on opposite sides ofthe motor 14 (see FIG. 17, which illustrates a bellows section 90 havingtwo bellows assemblies 64 in series). Exemplary embodiments of the sealand bellows sections 88 and 90 are illustrated in FIGS. 4 and 5A-B,respectively.

As illustrated in FIG. 4, the seal section 88 of the motor protector 16has various seal and protection elements disposed about the shaft 40within a housing 94. These elements are provided to protect the motor 14from undesirable fluid elements in the adjacent pump 12 and wellbore.Accordingly, the seal section 88 has a plurality of shaft seals, such asshaft seals 96, 98 and 100, disposed about the shaft 40 to seal andisolate the motor fluid 54 from the undesirable fluids (e.g., the wellfluid 68). The seal section 88 also has the thrust bearing 48 disposedabout the shaft 40 to accommodate and support the thrust load from thepump 12. A moisture absorbent assembly 102 also may be disposed aboutthe shaft 40 to remove the undesirable fluids from the internal fluid(i.e., the motor fluid 54 within the housing 94).

As discussed above, the internal fluid of the system 10 is positivelypressurized to prevent in-flow of the undesirable fluids through theshaft seals 96, 98, and 100. In a section 106 between the shaft seals 98and 100, a relief valve 104 is provided to release internal fluid fromthe system 10 when the internal pressure exceeds the maximum pressurethreshold. Accordingly, the present technique maintains the internalfluid within a certain positively pressurized pressure range to preventin-flow of undesirable fluids through the shaft seals 96, 98, and 100,while also allowing a pressure release when the internal pressureexceeds the maximum pressure threshold. This technique ensures thatfluid is pressurably repelled and ejected rather than allowing theundesirable fluids to slowly migrate into the system 10, such as in apressure balanced system. However, the present invention also mayutilize various pressure balancing assemblies to complement the seal andbellows sections 88 and 90, as discussed below with reference to FIGS. 6and 13-16. For example, the seal section 88 may include a labyrinth orbag assembly between the shaft seals 96, 98 and 100 (see FIG. 6, whichillustrates bag assembly 124 between shaft seals 116 and 118).

As illustrated in FIGS. 5A and 5B, the bellows section 90 of the motorprotector 16 has the bellows assembly 64 disposed in a housing 106,which may be coupled to the motor 14 at a coupling section 108 and toanother component at a coupling section 110. Inside the housing 106, thebellows assembly 64 is oriented such that the interior 66 is in fluidcommunication with the well fluid 68 through the ports 72. An externalfilter assembly 112 is disposed about the ports 72 to filter outundesirable elements within the well fluid 68. The exterior 70 of thebellows assembly 64 is in fluid communication with the motor fluid 54.The bellows assembly 64 also has a filter disposed between the bellowsassembly 64 and the motor 14. For example, a filter assembly 114 may bedisposed at the expansion stop 82 of the housing 84 to filter out motorshavings and other harmful elements. Accordingly, the filter assemblies112 and 114 filter out undesirable elements from the motor fluid 54 andthe well fluid 68 to protect the bellows assembly 64. In thisconfiguration, the motor fluid 54 contracts the bellows assembly 64 asit is injected into the motor 14, while the well fluid 68 acts againstthe bellows assembly 64 as the system is submersed into the well.

As discussed above, the bellows assembly 64 is movably disposed withinthe housing 84 between the expansion stop 82 and the contraction stop78. As the motor fluid 54 expands and contracts due to temperaturechanges, the bellows assembly 64 contracts or expands to a new restingposition, where the internal motor pressure is balanced against the wellpressure plus the spring force of the bellows. If the motor fluid 54expands, the bellows of this embodiment contracts accordingly. If themotor fluid 54 contracts, the bellows of this embodiment expandsaccordingly. The motor fluid 54 in this embodiment, therefore, remainspositively pressurized in relation to the well fluids 68, regardless ofwhether or not it has been expanded or contracted due to temperaturevariations.

The bellows assembly 64 also may utilize various spring assemblies andother biasing structures to facilitate pressurization of the motor fluid54. For example, as shown in FIG. 9, a spring assembly 300 may beincorporated into the bellows assembly 64 to complement the resistanceof the bellows assembly 64 and to increase the stroke of bellowsassembly 64 (thereby increasing the time and range in which the bellowsassembly 64 will maintain a positive pressure on motor fluid 54). Asillustrated by the contrasting orientations of the bellows assembly 64in FIGS. 2 and 5A-B, the orientation of the bellows assembly also can bevaried to accommodate a particular pumping system and application.

Moreover, as discussed in further detail below, the motor protectordevices of the present technique may be used alone or separate, induplicate, in series, in parallel, or in any suitable configuration toprovide optimal protection for the motor 14. For example, as illustratedin FIG. 17, a plurality of bellows assemblies 64 may be disposed inseries within the bellows section 90 of the system. In the embodiment ofFIG. 17, the bellows section 90 comprises two of the motor protectorstructures illustrated by FIGS. 5A-5B. The bellows assemblies 64 arearranged longitudinally adjacent one another in the bellows section 90,each bellows assembly 64 having a longitudinally adjacent set of ports72 and filters 12 for fluid communication with the well fluid 68. Theopposite side of each bellows assembly 64 is in fluid communication withthe motor fluid 54. The upper bellows assembly 64 is in direct fluidcommunication with the motor fluid 54 via the coupling 108. The lowerbellows assembly 64 is in fluid communication with the motor fluid 54through a conduit 115, which also may provide passage for the wiringassembly 87. Accordingly, the motor fluid 54 is positively pressurizedrelative to the well fluid 68 by the spring-force and well pressureexerted on both of the bellows assemblies 64. If additional internalpressure is needed to protect the motor fluid 54, then additionalbellows assemblies 64 can be incorporated into the bellows section 90.

The system 10 also may comprise a variety of conventional motorprotector components, such as a bag assembly and a labyrinth assembly.FIG. 6 is a diagrammatical cross-section of an alternate embodiment ofthe pumping system having such conventional motor protector elements. Asillustrated, the system 10 has the pump 12, the seal section 88, themotor 14 and the bellows section 90 sequentially intercoupled.

The bellows section 90 has the bellows assembly 64 oriented such thatthe interior 66 is in fluid communication with the well fluid 68, whilethe exterior 70 is in fluid communication with the motor fluid 54.Although FIG. 6 does not illustrate the various filters and otherprotection elements for the bellows assembly 64, the bellows section 90may include a variety of filters, seals, moisture absorbent assemblies,housings, bellow stops, and other desired bellows protection elementsconfigured to prolong the life of the bellows assembly 64, as previouslydescribed.

The seal section 88 has shaft seals 116 and 118 disposed about chambers120 and 122, which have a bag assembly 124 and a labyrinth assembly 126disposed therein to provide pressure balancing between the shaft seals116 and 118. The seal section 88 also may utilize a variety of otherpressure balancing components, such as conventional bag assemblies,conventional labyrinth assemblies, and various bellows and labyrinthassemblies of the present technique. A plurality of pressure checkvalves, such as valves 128 and 130, are also disposed in the sealsection 88 to control the positively pressurized fluid within the system10. For example, the valve 128 is configured to monitor the pressure andto trigger a backup oil supply when the pressure falls below the minimumpressure threshold in the motor 14 (e.g., 5 psi). For example, if thebellows section 90 fails to expand or contracted as in normal operation,then the valve 128 acts as a backup to ensure a desired pressure rangefor the motor fluid 54. The valve 130 is configured to monitor thepressure and to release the positively pressurized motor fluid 54 withinthe motor 14 when the internal pressure exceeds the maximum pressurethreshold. Accordingly, the valve 130 ensures that the O-ring seals inthe pothead, the joints, and various other components in the sealsection 88 are protected from excessive pressure differentials.

FIGS. 7 and 8 illustrate alternate configurations of the seal and bellowsections of the motor protector 16 of the system 10. As illustrated inFIG. 7, one embodiment of the system 10 has the seal section 88 and thebellows section 90 sequentially disposed between the pump 12 and themotor 14. The system 10 also has the optional monitoring system 92disposed adjacent the motor 14 and opposite the bellows section 90. Asillustrated in FIG. 8, the exemplary embodiment of system 10 also hasthe seal section 88 and the bellows section 90 sequentially disposedbetween the pump 12 and the motor 14. However, an additional bellowssection 131 is disposed below the motor 14 to complement the bellowssection 90 disposed above the motor 14. The system 10 also has theoptional monitoring system 92 disposed below the relatively lowerbellows section 131. Accordingly, the seal and bellows sections 88, 90and 131 may be oriented at various locations relative to the pump 12 andthe motor 14, while also including a plurality of such sections 88, 90and 131 to improve the effectiveness of the overall motor protectiontechnique. It also should be noted that the seal sections 88 illustratedin FIGS. 7 and 8 may include conventional motor protection components,such as those illustrated in FIG. 6.

It is expected that the bellows section, as discussed above andillustrated in FIGS. 5A-5B, may be reused in the system 10 with minimalrepair costs. There is no shaft below the motor, so mechanical wearshould be at a minimum, and the metal bellows will operate well down thestress strain curve, which should reduce fatigue and loss of springconstant force.

The system 10 also may have a variety of alternate configurations of thebellows assembly 64 for positioning the bellows about the shaft 40, asillustrated in FIGS. 11 and 12. For example, the bellows assembly 64 mayembody an annular or ring-shaped enclosure, which may be fixed at one orboth ends to provide a fixed seal and an expandable/contractible volume.Accordingly, the bellows assembly 64 avoids use of sliding seals, whichtypically cause leakage into the motor fluid. In this embodiment, thefluid pressures on opposite sides of the bellows assembly 64 may berelatively balanced rather than providing a significant pressuredifferential between the fluids. However, it is understood that a slightpressure differential, such as 5 psi, may be provided in thispressure-balanced configuration of the bellows assembly 64.

As illustrated in FIGS. 11 and 12, the bellows section 90 has thebellows assembly 64 disposed in a housing 132, which may be coupled tothe motor 14 at one of sections 134 and 136. For example, in theseexemplary embodiments, the motor 14 is coupled to section 134, while thepump 12 or another protector component (e.g., a bellows assembly, a bagassembly, a labyrinth assembly, etc.) is coupled to the section 136.

Inside the housing 132, the bellows assembly 64 is oriented such thatthe interior 66 is in fluid communication with the well fluid 68 throughthe port 138. Alternatively, if a labyrinth assembly, such asillustrated in FIGS. 13-16, is coupled to the section 136, then theinterior 66 may be in fluid communication with a desired isolation fluidconfigured to facilitate separation from the well fluid 68 in thelabyrinth assembly. In either configuration, a filter assembly 140 canbe disposed adjacent the port 138 to filter out undesirable elementswithin the well fluid 68 or the desired isolation fluid.

The exterior 70 of the bellows assembly 64 is in fluid communicationwith the motor fluid 54 via the ports 142 and 144. Alternatively, theexterior 70 may be in fluid communication with a second isolation fluidfor a second labyrinth assembly, a bag assembly, or any other desiredfluid separation assembly. As described in detail above, the bellowsassembly 64 also can include a variety of bellows protection elements,such as guides, seals, filters and absorbent packs (e.g., moistureabsorbent packs 146 and 148). The bellows section 90 also may compriseone or more shaft seals, thrust bearings, and various other seals andbearings. For example, the bellows section 90 may have shaft seals 150and 152 disposed about the shaft 40 on opposite sides of the bellowsassembly 64. A thrust bearing 154 is also disposed about the shaft 40adjacent the section 134.

As discussed above, the bellows assemblies 64 of FIGS. 11 and 12 arebalanced pressure bellows rather than a positively pressurized bellows,which is illustrated by FIGS. 2, 5A-B, 6, and 9. In operation of thebellows assemblies illustrated by FIGS. 11 and 12, injection andexpansion of the motor fluid 54 in the motor 14 (or other isolationfluid) and the exterior 70 causes the bellows assembly 64 to contract.In contrast, the pressure of the well fluid 68 (or other isolationfluid) causes the bellows assembly to expand. As the motor fluid 54expands and contracts due to temperature changes, the bellows assembly64 contracts or expands to a new resting position, where the internalmotor pressure is balanced against the well pressure plus any resistanceof the bellows. If the motor fluid 54 (or other isolation fluid)expands, the bellows of this embodiment contracts accordingly. If themotor fluid 54 (or other isolation fluid) contracts, the bellows of thisembodiment expands accordingly. Accordingly, bellows assembly 64substantially balances the pressures between the motor fluid 54 and thewell fluid 68 under a wide range of operating conditions, which includeboth expansion and contraction of the motor fluid 54. If a positivepressure differential is desired in the bellows assemblies 64 of FIGS.11 and 12, then a spring assembly, such as illustrated in FIG. 9, can beincorporated into the bellows assemblies 64 to prevent inward leakage ofundesirable elements such as the well fluid 68.

As noted above, the bellows assemblies 64 of FIGS. 11 and 12 may befixed at one or both ends. The embodiment illustrated in FIG. 11 has thebellows assembly 64 fixed to a member 156 at an end 158, while anopposite end 160 is free to expand and contract within the housing 132.As illustrated, the bellows assembly 64 has a generally annular orring-shaped geometry, which has inner and outer wall sections 162 and164 extending along inner and outer walls 166 and 168 of the bellowssection 90 from the member 156 to an opposite wall section 170 at theend 160. Accordingly, the opposite wall section 170 foldingly movesinwardly and outwardly as the pressure changes between the motor andwell fluids 54 and 68. The bellows assembly 64 also may include a stop,such as illustrated in FIGS. 5A and 5B, to prevent over extension of thebellows assembly 64. The internal components of the bellows section(e.g., component 172) also may act as a stop for the bellows assembly64. The particular length and spring stiffness of the bellows assembly64 may be configured for any desired operating conditions and wellenvironments. Additional bellows assemblies 64 also may be incorporatedinto the bellows section 90 to provide additional protection for themotor 14.

As illustrated by FIG. 12, the bellows assembly 64 also may have one ormore stepped sections, such as stepped section 174. The stepped section174 provides a fluid interface to facilitate expansion and contractionof the bellows assembly 64. In this exemplary embodiment, the bellowsassembly 64 is fixed at both ends to members 156 and 172, while thestepped section 174 is movable as the well and motor fluids 54 and 68expand and contract in the interior 66 and exterior 70 of the bellowsassembly 64, respectively. The stepped section 174 acts as a fluidinterface between large diameter and small diameter bellows sections 176and 178, which are configured to move along the outer and inner walls168 and 166, respectively. The particular lengths and spring stiffnessof the bellows sections 176 and 178 may be configured for any desiredoperating conditions and well environments. Additional bellowsassemblies 64 also may be incorporated into the bellows section 90 toprovide additional protection for the motor 14.

The system 10 also can include one or more labyrinth assemblies, bag orbladder assemblies, or other conventional motor protector assemblies toprotect both the motor 14 and the bellows assembly 64. Moreover, thesystem 10 can comprise the positively pressured bellows assembly 64shown in FIG. 2 (for example) along with the balanced pressure bellowsassembly 64 shown in FIGS. 11, 12, and 16B.

Additionally, as illustrated in FIGS. 13-16, the motor protector 16 ofthe system 10 may comprise a multi-orientable labyrinth assembly 180(i.e., operable in multiple orientations), which may be used atone or incombination with the bellows assembly 64 or other components. Asdiscussed in detail below, the multi-orientable labyrinth assembly 180has one or more conduits that extend in multiple directions to ensurefluid paths having peaks and valleys in multiple orientations of themulti-orientable labyrinth assembly 180. Accordingly, the peaks andvalleys in these various orientations ensure continuous fluid separationin all orientations of the multi-orientable labyrinth assembly 180 basedon differences in specific gravity. In the embodiment illustrated inFIG. 13, the system 10 has the multi-orientable labyrinth assembly 180disposed between the pump 12 and the motor 14.

As described in other embodiments of the system 10, a variety of seals,couplings, bearings, filters, absorbents, and protection devices may beprovided to protect and prolong the life of the motor 14. Accordingly,the system 10 may include couplings 182 and 184, a thrust bearing 186,and a solids processor 188. The exemplary solids processor 188 isdisposed in a chamber 189 between the pump 12 and the motor protector 16to prevent solids from entering the multi-orientable labyrinth assembly180 and from generally corrupting the motor projection devices in themotor protector 16. As illustrated, the solids processor 188 includes avariety of solids separators, such as shedder 190 and shroud 194, whichprevent solids from settling on and damaging bearings and seals such asshaft seal 192. The solids separator 190 throws or sheds solidsoutwardly from the shaft 40 and shaft seal 192. The shroud 194, whichmay embody an extended length shedder in a deviated orientation, alsoprevents solids from settling near the shaft 40 and damaging the shaftseal 192. The solids processor 188 also includes one or more flow ports196 that allow solids to escape into the wellbore.

The multi-orientable labyrinth assembly 180 comprises amulti-directional winding of tubing, which is fluidly coupled to themotor and well fluids 54 and 68 (or other isolation fluids) at ends 198and 200, respectively. As illustrated, the ends 198 and 200 arepositioned in respective opposite ends 202 and 204 of the motorprotector 16. The end 198 is coupled to a port 206 extending to themotor 14, while the end 200 is positioned openly within the motorprotector 16. The end 200 also includes a filter 208 to prevent solidsand other undesirable elements from entering the multi-orientablelabyrinth assembly 180. The well fluid 68 enters the motor protector 16via conduit 210, which extends from the chamber 189 to the end 202 ofthe motor protector 202. The conduit 210 also can include one or morefilters, such as filter 212, to prevent the inflow of solids into themotor protector 16.

In operation, the multi-directional winding of the multi-orientablelabyrinth assembly 180 maintains fluid separation of the motor and wellfluids 54 and 68 by using the differences in specific gravity of thefluids and multi-directional windings. As illustrated in FIGS. 14 and15, the multi-orientable labyrinth assembly 180 has a plurality ofcrisscrossing and zigzagging tubing paths, which extend in multipleorientations (e.g., 2-D, 3-D, or any number of directions) to ensurethat the fluids go through upward and downward movement regardless ofthe orientation of the system 10. For example, the multi-orientablelabyrinth assembly 180 may be operable in a vertical wellbore, ahorizontal wellbore, or any angled wellbore. The multi-orientablelabyrinth assembly 180 also can be disposed in a variety of submersiblepumping systems 10, including those illustrated in FIGS. 1-13 and 16.Moreover, a plurality of the multi-orientable labyrinth assemblies 180may be disposed in series or in parallel in various locations within thesystem 10.

In one system configuration, such as illustrated by FIGS. 2, 5A-B, 6, 9and 10, the embodiment illustrated in FIG. 14 may be disposed in achamber between the bellows assembly 64 and the well fluid 68 to protectthe bellows assembly 64. In the foregoing system configuration, the pump12 and the motor 14 can be positioned side by side, while the bellowsassembly 64 and the multi-orientable labyrinth assembly 180 are disposedadjacent the motor 14. In contrast, the embodiment illustrated in FIG.15 is configured for positioning about the shaft 40 in a centralprotector configuration, such as illustrated by FIGS. 11-13 and 16. Inthis central configuration, the multi-orientable labyrinth assembly 180has an annular or ring-shaped geometry, which provides an inner conduit214 for the shaft 40. In both embodiments of FIGS. 14 and 15, themulti-orientable labyrinth assembly 180 may include one or morecontinuous tubes, which are interwoven in zigzagging andmulti-directional patterns terminating at opposite ends of the labyrinthassembly 180. Moreover, the dimensions of the tubing, the density of thewindings, and other geometrical features may be tailored to the specificsystem 10 and downhole environment.

The multi-orientable labyrinth assembly 180 also has an additionalfeature, as compared to conventional two-dimensional labyrinths. Intwo-dimensional labyrinths, the oil/well fluid interface occurs withinthe labyrinth chamber and not within one of the labyrinth tubes. In themulti-orientable labyrinth assembly 180, the interface may occur in therelevant chamber, but it may also occur within the multi-oriented tube180 thereby enabling the assembly 180 to be used in any orientation (aspreviously discussed).

In an exemplary embodiment of the system 10, a plurality of theforegoing motor protector and seal devices may be disposed in parallelor in series within the system 10. FIGS. 16A and 16B, which are brokenalong line 215-215 for illustrative purposes, are cross-sectional viewsof an exemplary embodiment of the motor protector 16 having a pluralityof motor protecting and sealing assemblies disposed between the pump 12and the motor 14. As illustrated, the motor protector 16 includes asolids processing section 216 adjacent the pump 12, a sand shield orseal protection section 218 adjacent section 216, a multi-orientablelabyrinth section 220 adjacent section 218, a bellows section 222adjacent section 220, a conventional labyrinth section 224 adjacentsection 222, and a thrust bearing section 226 adjacent section 224.

The solids processing section 216 can include a variety of shrouds toshield the seals, and various shedders and ports to shed and eject thesolids into the wellbore, as discussed above. For example, the section216 includes outer and inner shedders 228 and 230, respectively. Thesand shield section 216 may comprise a variety of filters and shields,such as shroud 232, which prevent sand and other particulate matter fromcorrupting the system 10 (e.g., seal body 234).

The labyrinth section 220 comprises one or more of the multi-orientablelabyrinth assemblies 180, such as illustrated in FIGS. 13 and 15, whichmay be coupled in series or in parallel within the section 220. Thelabyrinth section 220 also may comprise a conventional labyrinth orelastomeric bag assembly, such as illustrated in the labyrinth section224 (see also FIG. 6, which illustrates conventional bag and labyrinthassemblies 124 and 130, respectively).

The bellows section 222 comprises one or more of the above-describedbellows assemblies 64, which will typically be a balanced pressurebellows, but may also be a positively pressurized bellows. In theexemplary embodiment of FIGS. 16A and 16B, the bellows assembly 64 is abalanced pressure bellows, such as illustrated in FIGS. 11 and 12.Accordingly, the bellows assembly 64 is fixed at one or both ends of thebellows section 222.

The foregoing sections 218, 220, 222, 224 and 226 are intercoupled andsealed via seal bodies 234, 242, 244 and 246, each of which comprises ashaft seal 236, a bearing 238, and a conduit 240 for fluidlyintercoupling the adjacent sections. The seal bodies 234, 242, 244 and246 also can include a variety of other seals, bearings and conduits.The thrust bearing section 226 also comprises a thrust bearing 248 andother desired seals, bearings and conduit structures.

In addition to those components illustrated in FIGS. 16A and 16B, thesystem 10 may also comprise a positively pressured bellows assembly 64located below the motor 14, as shown in FIGS. 2 and 6 for example.

Accordingly, the present invention may embody a variety of systemconfigurations and motor protectors 16 and corresponding devices, suchas the bellows assembly 64 and the multi-orientable labyrinth assembly180. As described above, the bellows assembly 64 may embody either apositively pressurized system or a balanced pressure system. Theforegoing motor protectors 16 and corresponding devices may be usedalone or together in any configuration, including multiples of eachdevice and conventional motor protectors. Moreover, one or more of themotor protectors 16 can be disposed above, between or below the pump 12and the motor 14. For example, if a balanced pressure bellows isdisposed above the motor 14 or between the pump 12 and the motor 14,then a positively pressurized bellows may be disposed below the motor 14in fluid communication with the well fluid. Moreover, any of theforegoing motor protectors 16 and corresponding devices may befunctionally combined in series or in parallel, or any combinationthereof.

It will be understood that the foregoing description is of preferredexemplary embodiments of this invention, and that the invention is notlimited to the specific forms shown. These and other modifications maybe made in the design and arrangement of the elements without departingfrom the scope of the invention as expressed in the appended claims. Forexample, the bellows assembly may be replaced or complemented by anysuitable pressure inducing assembly, such as a hydraulic piston assemblyor a spring-assisted piston assembly.

1. A motor protector for a submersible pumping system, comprising: ahousing positioned between a submersible centrifugal pump and asubmersible motor to form an electric submersible pumping system; abellows assembly within the housing, the bellows assembly having a firstand a second accordion-like enclosure each able to expand and contractwhile isolating an internal motor oil, the first accordion-likeenclosure being of a different diameter than the second accordion-likeenclosure; and an attachment structure connecting at least one end ofthe bellows assembly to the electric submersible pumping system.
 2. Themotor protector of claim 1, further comprising a spring memberpositioned to pressurize the internal motor fluid to a positive pressurerelative to an external well fluid pressure.
 3. The motor protector ofclaim 1, wherein the bellows assembly is free of sliding seals.
 4. Themotor protector of claim 1, further comprising a filter positioned tolimit movement of particulates into the bellows assembly.
 5. The motorprotector of claim 1, further comprising at least one stop to limitmovement of at least one of the first and the second accordion-likebellows.
 6. The motor protector of claim 5, wherein the at least onestop comprises a bellows contraction stop.
 7. The motor protector ofclaim 5, wherein the at least one stop comprises a bellows expansionstop.
 8. The motor protector of claim 2, wherein in the spring member isincorporated into at least one of the first and the secondaccordion-like bellows.
 9. A method of protecting a motor in asubmersible pumping system, comprising: providing a bellows assemblyhaving accordion-like enclosures of different diameters; positioning thebellows assembly within a motor protector housing to form a motorprotector able to isolate an internal motor dielectric oil; connectingthe motor protector to a submersible motor to enable flow of theinternal motor dielectric oil between the bellows assembly and thesubmersible motor; and operatively coupling a submersible centrifugalpump to the submersible motor on an opposite side of the motorprotector.
 10. The motor protector of claim 9, further comprisingpressurizing the internal motor dielectric oil to a positive pressurerelative to an external well fluid.
 11. The motor protector of claim 9,further comprising forming an axial passage through the bellowsassembly; and positioning a drive shaft through the axial passage. 12.The motor protector of claim 9, further comprising securing the bellowsassembly in the motor protector housing without sliding seals.
 13. Themotor protector of claim 9, further comprising filtering the internalmotor fluid to prevent contaminants from entering the bellows assembly.14. The motor protector of claim 9, further comprising positioning stopswithin the motor protector housing to limit movement of the bellowsassembly.